Compressor assembly

ABSTRACT

An air compressor assembly including a centrifugal impeller discharging air through a vaneless diffuser and a plurality of conical diffusers into an air collecting plenum. An air cooler is connected to the open end of the plenum to receive the air therefrom.

limited States Patent 1 Ehlinger Sept. 18, 1973 COMPRESSOR ASSEMBLY [75] Inventor: Arnold H. Ehlinger, Hales Corners,

Wis.

[73] Assignee: Allis-Chalmers Corporation,

Milwaukee, Wis.

[22] Filed: Feb. 14, 1972 [21] Appl. No.: 226,160

[52] U.S. Cl 415/178, 415/207, 415/209, 415/219 A 1 Ch u 4 ma matic 14.2913 [58] Field of Search ..'...415/219 C, 207, 206, 415/219 A, 178, 179,209

[56] References Cited 1 UNITED STATES PATENTS 3,211,362 10/1965 Laskey et al 415/178 3,420,435 1/1969 Jarosz et al. 415/207 FOREIGN PATENTS OR APPLICATIONS 1,195,142 5/1959 France 415/179 456,976 11/1936 Great Britain 725,254 3/1955 Great Britain 415/207 Primary Examiner1-lenry F. Raduazo Attorney-John P. Hines et a1.

[57] ABSTRACT An air compressor assembly including a centrifugal impeller discharging air through a vaneless diffuser and a plurality of conical diffusers into an air collecting plenum. An air cooler is connected to the open end of the plenum to receive the air therefrom.

2 Claims, 2 Drawing Figures air coolers are needed between the stages of the multistage compressor. Without these intercoolers additional power to drive the compressor and perhaps additional stages would be required. Older compressor systems used two or more uncooled machines with an intercooler between the discharge and inlet of connected machines.

Even with the use of intercoolers, multi-stage compressors are quite large. It is applicant's intention to develop a compressor assembly including an integral air cooler of a reasonable size and efficiency which can be utilized as a single stage compressor or as a stage of a multi-stage compressor.

It is known in the prior art to provide a compressor with vaned radial diffusers followed by aplenum guide vanes to guide the air to an air cooler.lt is also known in the prior art to provide a system consisting of vaneless radial diffusers followed by a log spiral collecting plenum to deliver the air to an aircooler. Although a vaned diffuser is advantageous in certain applications, it does tend to limit the operating range of a compressor more so than a vaneless diffuser. It is well known that a log spiral collecting system is bulky and expensive to manufacture. In the assembly set forth in this disclosure the flow of air from a vaneless diffuser through a plurality of channels each of which feeds a conical diffuser. This provides greater diffusion than a vaneless difi'user alone and eliminates the need for the log spiral collector. I

It is, therefore, the general object of this invention to provide a compressor assembly utilizing both vaneless and conical diffusers with the air discharging into a plenum having a cooler integrally connected thereto.

A more specific object of this invention is to provide a compressor assembly of the hereinbefore described type of reasonable size to permit the assembly to be utilized as a stage of a multi-stage compressor utilizing intercoolers.

It is an additional object of this invention to provide a compact efficient system for delivering air from the outer diameter of a compressor impeller to an intercooler of a cooled multi-stage compressor.

These and other objects of the subject invention will become more fully apparent as the following description is read in light of the attached drawing wherein:

FIG. 1 is a cross sectional view of a compressor assembly constructed in accordance with this invention taken along thc line l--l of FIG. 2; and

FIG. 2 is a cross sectional view taken along the line ll-ll of FIG. 1.

Referring to the drawings, a centrifugal compressor impeller generally designated 6 is supported for rotation by a shaft 7. The impeller 6 is located within a compressor casing generally designated 8. Walls of the compressor casing define an annular vaneless diffuser 9 located about the radially outer end of the impeller 6. As herein shown for purposes of illustration there are four conical diffusers 11 formed as integral parts of the compressor casing equally spaced circumferentially about the impeller 6. The inner ends of the conical diffusers are in air communication with the radially outer end of the vaneless diffuser 9. The discharge or larger end of the conical diffusers 11 are in air communication with a plenum generally designated 12.

The plenum 12 is connected to the compressor casing 8 in any conventional manner and completely surrounds the discharge ends of the conical diffusers 11. One end of the plenum 12 is open to the inlet of an air cooler generally designated 13. One of the conical diffusers as shown in FIG. 1 discharges the air therethrough directly toward the intercooler. However, the remaining conical diffusers discharge the air therethrough at an angle from the inlet to the intercooler. Therefore, guide vanes 14 are provided at these three conical diffuser discharge openings to guide the discharged air into the air cooler intake.

The compressor assembly, above described, can be advantageously utilized as a single stage compressor or as a stage of a multi-stage compressor. In either instance the gas enters the compressor inlet 16 where the impeller 6 increases its internal and kinetic energy. About one-half of the work done by the impeller is in the form of kinetic energy. After the gas leaves the impeller it flows through the vaneless diffuser 9 where a part of its kinetic energy is converted to internal energy producing an increase in static pressure. At the outer diameter of the vaneless diffuser 9 the gas is collected and fed into the conical diffusers where there is a further conversion of kinetic energy and a further increase in pressure. At the outlet of the conical diffusers, there is a small amount of kinetic energy remaining and it is assumed that this energy is dissipated (without a further increase in pressure) as the gas enters the plenum 12. The gas is then directed by the guide vanes 14 into the cooler 13.

Without the conical diffusers 11, the vaneless diffusers 9 would be required tobe much longer and would alsorequire a log spiral plenum resulting in a much larger assembly.

As an example, the height of a compressor constructed in accordance with this invention would be approximately l5 percent less than the height of a compressor incorporating a vaneless diffuser and a log spiral plenum and having substantially equal capacities. A slight reduction in axial length of this compressor is also achieved.

A decrease in the height of a compressor has decided benefits. The reduction in height of the lower half casing (from base to horizontal joint) makes that part easier to ship. The reduction in height of the upper half casing reduces the head room required for removal of the upper half casing during maintenance.

Furthermore, there would be a reduction in cost of manufacture because of the small size and less complicated structure.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as folintegral gas cooler located in said plenum and guide means about said circumferentially spaced conical diffusers for directing the discharge gas from said conical diffusers into said gas cooler.

2. The compressor set forth in claim 1 and further comprising guide means including guide vanes located within said plenum adjacent the discharge from said conical diffusers and positioned to guide the gas discharged therefrom in the direction of the gas cooler inlet. a: 

1. A compressor assembly comprising: a compressor casing having a substantially axially disposed gas inlet; an impeller supported for rotation within said casing about said axis and located to receive gas from said inlet, diametrically opposed points on said casing being equidistant from said axis; walls of said casing defining an annular vaneless difuser surrounding the radially outer end of said impeller to receive gas discharge therefrom, the radial dimension of said diffuser from said axis being substantially greater than the radius of said impeller; a plurality of circumferentially spaced conical diffusers associated with said casing having their smaller ends in gas communication with said vaneless diffuser, the outer ends of said conical diffusers providing an outlet for the gas from said impeller; walls defining a plenum connected to said casing enclosing said conical diffusers to receive the gas therefrom, the axial dimension of said plenum being substantially equal to the axial dimension of said casing; and an integral gas cooler located in said plenum and guide means about said circumferentially spaced conical diffusers for directing the discharge gas from said conical diffusers into said gas cooler.
 2. The compressor set forth in claim 1 and further comprising guide means including guide vanes located within said plenum adjacent the discharge from said conical diffusers and positioned to guide the gas discharged therefrom in the direction of the gas cooler inlet. 